Method of and machinery for forming pavements



NOV. 8, 1932. w M VENABLE 1,887,341

METHOD OF AND MACHINERY FOR FORMING PAVEMENTS Filed Feb. 7. 1928 2Sheets-Sheet 1 wnwess INVENTQR W4 01124421) in Wm 0 mar/1.0

Nov. s, 1932. w. M, VENABLE 1,887,341

METHOD OF AND MACHINERY FOR FORMING PAVEMENTS Filed Feb. 7, 1928 2Sheets-Sheet 2 WITNESS INVENTOR Patented Nov. 8, 1932 UNITED STATESPATENT OFFICE WILLIAM ILVENABLE, OI PITTSBURGH, PENNSYLVANIA, ASSIGNOBTO BMW-KNOX COMPANY, OF BLAWNOX, PENNSYLVANIA, A CORPORATION OF NEWJERSEY METHOD OF AND MACHINERY FOR FORMING rAVE'MEN'IS Application filedFebruary 7, 1928. Serial No. 252,528.

My invention relates to improvements in methods of and machinery forforming pavements, and finds practical application in the forming ofconcrete highways. In that par ticular' application I shall describe it.The object is the production of a well compacted and durable pavementwhose surface is relatively free of unevenness and irregularity, andfree particularly of fortuitous areas of depression.

\The accompanying drawings illustrate somewhat diagrammatically aroad-building machine in which and in the operation of which myinvention is embodied and achieved. Fig. I is a View of the'apparatus inside elevation, resting in position for operation, upon the road railsof a road under construction. Fig. II is a View of the machine inplan-from above. Fig. III is a view in vertical and transverse section,on a broken plane indicated by the line III-III, Fig. II. IV is afragmentary view in vertical and transverse section, on the planeindicated at IVIV, Fig. I.

My invention is applicable to the finishing of roadways, so as to obtaina proper spreading and smoothing of the concrete surface, with economyand without inconvenience. The primary concern is to produce frommatcrial which from the necessities of the case is non-uniform incomposition and character a finished structure which is to the highestattainable degree uniform. In the practice of building concrete roads asit is now wide-- ly carried on, the concrete as it leaves the mixer is amechanical mixture of stone, or other coarse aggregate, sand or otherfiner aggregate, cement, and water. This mixture is produced in batches;that is to say, a meas-. ured quantity of stone, a measured quantity ofsand, a measured quantity ofcement, and

a measured quantity of water are stirred together in the mixer. If itwere possible always to have raw material of exactly the same qualityand of the same degree of fineness, and always by practical means ofmeasurement to introduce exactly the same quantity of each componentinto each batch, the concrete produced would be uniform in consistency,batch after batch; and, of course, uniform concrete uniformly spreadmight be expected to afford a uniform road. In practice, however, it isim ossible to obtain the raw material with per ect uniformity of size ofparticles, of degree of fineness, and of qualit and character; andespecially it is impossible, under practical conditions, to haveuniformity in the quantity of water present in successive batches.Always there is moisture present in the sand and stone employed, and themoisture so present is variable in quantity. This variability of watercontent disturbs the proportioning of the batch, and, particularly inthe matter of water component, has the effect of causing successivebatches to be irregular beyond control in thematters of wetness andconsequent fluidity, The water content of the completed batch as it isdumped from the mixer to the road surface may vary in a degree as greatas 40% of the actually desired quantity.

In any case, the road-spreading operation requires a mixed concrete ofgreat fluidit a concrete whose water content is larger t an necessary toeffect setting. In the road-building operation so much of the surpluswater as may be, should be removed, and this without removing with thewater any appreciable part of the cement. The water content of thebatches being variable beyond practical control, the removal of surpluswater to leave a uniform body of concrete is diflicult, because thequantity of the surplus is variable.

In road building it is necessary to employ machinery to spread theconcrete; the slow and laborious hand spreading is inadequate, to meetthe demands of speed and quantity. Ooncretespreading machinery hithertoemployed acts upon the concrete as though it were uniform in compositionand consistency, and as thou h its water content always were the same. IIachine-spread roads, when finished, are liable to manifest undesiredirregularities of surface, and particularly de- 1 pressions of surface,in which water will lie. The road on that account is inferior and isliable to more rapid deterioration.

Let it be assumed that two successive batches of mixed concrete arespread upon the sub-grade of a road, and that one batch has more waterin it than the other. Such a condition may easily exist in what isconsidered a well conducted job. Let it be assumed that the ratio ofcement, sand, and

stone used is 1:2:4, by volume. To mix 'theseeqlualities of the solidcomponents to the foot of concrete.

tel

It is manifest that, if the excess quantity of water in the wet batch isnot worked out before the final spreading operation either the concretein the portion of the road produced from the wet batch will berelatively porous,

- or some surplus water will escape or be worked out subsequent to thespreading operation. In the latter event, although the grade and Y I thesurface may have been correct, as left by the finishing machine, unequalsettlement continues and the surface is found irregular half an hourlater. In point of fact, such settlement actually occurs in very manycases in concrete roads as ordinarily built. The settlement is notuniform, but occurs in spots, so that the finished and hardened roadpresents an uneven surface, with numerous hol lows, below the normalsurface. The depth of these hollows due to this cause may be as great asone quarter, or even one half an inch.

- Although irregularities of surface are commonly produced by faultyfinishing due to other causes, as well as to lack of uniformity in watercontent, I have perceived such irregularities of surface as cannot beeli' inated by great care in the manipulation of ices now in use to bechiefly and primarily uhto the variation in the water content ofadjacent portions of the layer of concrete when freshliy spread; and Ihave further perceived that a jacent portions of a road may differ inthe matter of hardness and of friability, because of the differences inwater content in the layer of concrete when spread. My invention lies inmethod and in machine which, instead of treating the concrete as thoughit were uniform in content and consistency from batch to batch asreceived from the mixer, spreads the concrete in a manner which rendersit more instead of less uniform, and, removes from the concrete as it isspread a greater or less quantity of water, according as the particular7,

batch is relatively wet or relatively dry; and so I produce a road ofbetter uniformity, more satisfactory and more durable.

Referring to the drawings, a carriage 1 of suitable construction ismounted upon wheels 2, to travel along the rails 3, such as arecustomarily provided, both to carry the road-fin-' ishing machine, andto afford temporary walls or forms, between which the concrete is sread, and, until it has hardened, confined. he carriage may beunderstood to be equi ped with a' prime mover. This ordinari y will be aasoline engine, thou h manifestly it mightie a prime mover 0 anothersort, an electric motor, for exam le. In the drawings I showdiagrammatica y a sprocket wheel 4, which may be understood to be drivenby the prime mover, and I have diagrammatically indicated operativeconnections with this sprocket wheel, for driving a shaft 5, mountedtransversely in carriage 1. From the prime mover, and conveniently fromthe shaft 5, the carriage may be driven along the rails 3, throughsuitable driving connections; such, for instance, as those shown inFigs. I and II. Shaft 5 is equipped with a bevelled gear wheel 6, and agear wheel 7 is integrated with one of the wheels 2 of the carriage. Aconnecting rod 8 equipped at one end with a bevel gear 9 and at theother with a worm 10, simultaneously engages gear wheels 6 and 7 andtransmits rotation to the carriage wheel. The drive may bealternatelyforward, in the direction indicated by an arrow, Fig. I, orrearward.

The carriage is equipped with a plurality of rows of pressure shoes, inthis instance two rows, which extend row by row transversely, and arespaced apart row from row in the direction of machine'travel. The shoesare singly reciprocable in vertical direction. The shoes of the forwardrow are indicated by the numeral 11, those of the second row by 12. Asbest seen in Figs. II and III, these shoes are conveniently rectangularin plan; their ne er surfaces are plane surfaces, or approxim tely planesurfaces, extending horizontally, or approximately horizontally, andconforming in these respects to the surface to which the concrete is tobe shaped. Their forward lower edges are rounded. The shoes are situatedside by side in close succession. The shoes are conveniently formed assteel castings. Those of the forward row are preferably wider in theirfront to rear extent than those to the rear. The shoes of the front rowadditionally are equipped with vertically standing plates 13 whichconstitute extensions of their front faces and which serve as limitingand pushingwalls for the.

soft concrete. The shoes are vertically reciprocable between suitableguides, and these guides may be beams such as 14, constituting part ofthe carriage structure.

Means are provided for reciprocating the shoes 11 and 12, causingsucceeding shoes in the row to rise and descend successively, and foreffecting reciprocation throughout a range so limited and defined as -tospread and press the concrete to the desired form and position. It is amatter of simple engineering to provide for such reciprocation of thepressure shoes, and the means which I show will be understood to beexemplary of suitable means to that end.

The shaft 5 is conveniently mounted in an intermediate position in thelength of the carriage, and at a substantial interval above ticallyabove the forward row. The shaft 15 is driven from shaft 5 andsimultaneously with shaft 5, and means to that end, in the form of asprocket chain drive 16,. are dia grammatically indicated in Fig. I. f

The shaft 5 carries a series of eccentrics 17 and the shaft 15 carries aseries of eccentrics 18, and each eccentric is engaged by a block 19(2(1) and to the blocks 19 and 20 the shoes 11 and 12 are severallypivotally secured. The eccentrics through such connections effect thelimited reciprocation of the shoes, and manifestly the positioning ofthe succeeding eccentrics upon the shafts determines the intervals atwhich .the individual shoes succeed one another in their rise anddescent.

Shaft 15 extends at a somewhat greater interval than does shaft 5 abovethe level of i the rails 3, the eccentrics 18 borne by shaft 15 arelarger than those borne by shaft 5, and-the driving connections areindicated to be such in character that shaft 15 rotates at slower speedthan shaft 5. Accordingly the range of reciprocation of shoes 11 isgreater than that of shoes 12, a feature which though not essential isdesirable. The positions of the two shafts 5 and 15 are minutelyadjustable in vertical direction, by means of the slot and boltconnections indicated at 21, between the standards in which they arejournaled and the frame of the machine.

The construction and adjustment are such that each shoe 11 comes to thelimit of its downward thrust with its nether surface slightly higherthan the ideal surface to which the concrete is being shaped. Thisparticular position, being by the means described adjustable, will bedetermined in each particular case according to circumstances,

and primarily according to the thickness of the layer to which theconcrete is to be spread. The shaft 5 is so minutely positioned in itsvertical adjustment that the shoes 12 come to their limit of downwardthrust in a surface more closely approaching, but still slightly higherthan the ideal surface.

The shoes 11 are preferably of greater extent in front and reardirection than are the shoes 12. They are heavier, and, as has beenexplained,'their range of reciprocation is greater.

To the rear of the shoes 12 the machine frame carries a beam 22extending transversely across the width of the space between the wheels,whose nether surface is of considerable extent in forward 'and'rear d1--rection and whose nether surface conforms face, which comes. intocontact with the concrete. The plates with which it is shod may berenewable and replaceable.

At the front of the machine ard members 24 are fixed. These afford 1neffect upward continuations of the vertical inner faces of the rails 3.At their forward tips they are turned and extend obliquely across thetreads of the rails 3. These guard members hold the concrete and preventit from spreading laterally, and they keep the rails clear for theadvancing machine.

In operation the rails are set, the machine placed on the rails, and,the sub-grade having been properly prepared, concrete is dumped from themixing machine in front of the finishing machine, and the finishingmachine is advanced upon the roughly spread-out, mushy mass. As themachine advances, the shoes 11 and 12 work up'and down, and in each rowthe succeeding shoes work successively: One descends, then the next, andthe next; and presently they rise again and descend again in the samesuccession. The first row of shoes acts on the mass of concrete both bypushing and treading, and shapes it to a layer of approximately thedesired thickness. The second row of shoes, actin in like manner,reduces it more nearly to t e exact, desired thickness, and, finally,the beam 22 brings the layer to the ultimate desired thickness and givesto it its surface character.

The shoes 11, approximately flat over their nether surfaces and roundedat their forward edges, both press the concrete downward and pushforward the surplus. There will be some flowing of the concrete rearwardbeneath the shoes 11 and some consequent rising of the mass to rearwardof the down-pressed shoe. The shoe is however of sufficient length inthe direction of travel, to prevent any considerable movement of thatsort. The fact will be particularly noted that the concrete is morethoroughly worked beneath the plurality of 'vertically moving shoes thanit would be, were the several shoes merged in a single andcontinuousbar, and more thoroughly than would be the case were such asingle bar reciprocated horizontally in transverse direction. And inthese respects the method is distinguished from that now commonlyperformed.

As the machine advances, the body of concrete immediately to the rear ofthe line of shoes 11 is at approximately the proper grade; the minuteadjustment of the shoes 11 has, however, been such that the bod issomewhat above that proper grade. he value of the excess will in a givencase be proportioned to the thickness of the layer which is beingspread.

Between the rows of shoes 11 and 12 there is a stretch of concrete,reduced approximate- 1y to grade, but which has not yet received itsfinal shaping and finishing. The body of concrete in this stretch is ina state of constant, though slight, movement, imparted to it by theshoes reciprocating immediately to the front and immediately to therear. The effect is to compact the mass, causing water to work upwardand flow away. The com- 39 ponent solid particles of the mass are notwidely displaced. The operation is unlike that known as puddling. Thereis no kneading of the mass. The particles rock and tip one upon another,they move apart and together again through very slight intervals, butthere is no appreciable sliding. In consequence, the particles assumepositions of closer fit, and the water alone percolates upward to thesurface. If the concrete has 39 a relatively large water content, thewa- I ter will escape more freely, and that without carrying away anysubstantial amount of cement. And because of the rise and escape ofwater in this region, the body of concrete upon which the shoes 12 workis stiffer and firmer than that upon which the shoes 11 work.Furthermore, the compacting efiect is greatest at the bottom of thelayer. From that part the water is, by the minute movement described, inlargest measure expelled.

When then the shoes 12 have acted upon the layer, and the bar 22 hasfollowed, the layer,

although in its upper part it contains somewhat more water than in itslower part, will still not contain any such large quantity of surpluswater as to cause any considerable amount of subsequent settling of thespread and compacted layer.

The shoes 12 as here shown are of less extent in the direction ofcarriage travel than the shoes 11. The beam 22 is of such extent in thedirection of carriage travel that, as it holds down the now relativelystifi concrete, there is no flow of concrete to rearward beneath it andno consequent rise of concrete behind it.

The shoes 11 are of such dimensions,-and preferably the shoes 12 alsoare of such dimensions and so related in their period of reciprocationto the speed of advance of the machine, that the areas pressed uponsuccessively by each shoe are overlapping areas.

Necessarily it is true of the machine when operating in the mannerdescribed, that concrete gradually accumulates, not only in front J ofthe row of shoes 11, but also in front of apart parallel transversestrips to successive the row of shoes 12. When such accumulations haveincreased to a considerable amount, the parts 11, 12, and 22 are raisedbodily and brought to position again to rearward of the accumulationwhich had gathered immediately in front of the beam 22. Thisresetting ofthe work-engaging parts is, in the machine here illustrated, effected bylifting the whole carriage body and placing it again on the rails at apoint to rearward. The machine is then caused to advance again,operating as before. In practice, in laying a road nine or ten inchesthick, the machine will advance thirty feet or more, before theaccumulations make resetting desirable. The machine then is reset fiveor six feet to rearward. Thus the accumulations are not wasted but arecarried forward and incorporated in the road as it is progressivelyshaped and finished.

I call attention to the fact that in the operation of my machine thereis no transverse racking strain exerted upon the rails 3. They standfirm at all times. This results in a better compacted body of concrete,more accurate cooperation of shaping instrumentalities, and a betterjob. Incidentally, deterioration of equipment is less rapid.-

I claim. as my invention:

1. The method herein described of spreadin g forward supplies ofconcrete heaped upon the sub-grade of a road and bringing theWorked-upon body to desired contour, which consists in subjecting themass step by step, and over successive longitudinally overlappingrelatively narrow transversely fractional areas to vertical pressure andat the same time restraining it to rearward of such areas from upwardflow.

2. The method herein described of spreading to desired contour concreteheaped upon the sub-grade of a road and removing from the spread-outconcrete :1 content of superfluous water which consists in subjectinglocalized areas of the layer along two spaced compressive strains.

3. In apparatus for spreading to layer form concrete heaped upon thesub-grade of a road, a transverse row of vertically reciprocablepressure plates, means for causing the said row of plates to advanceupon and to engage immediately the heaped concrete, and means forreciprocating the pressure plates through a definite and predeterminedrange, the means for causing the plates to advance and the means forreciprocating the plates'being correlated, whereby each plate in itsadvance exerts pressure over overlapping areas.

4. In apparatus for spreading to layer form concrete heaped upon thesub-grade of a'road,

. a transverse row of vertically reciprocable pressure plates, means forreciprocating said plates in alternation through a definite andpredetermined range, and means for causing the said row of plates toadvance upon and to engage immediately the heaped concrete, the meansfor reciprocating the plates and the means for causing the row of platesto advance being correlated, whereby each plate in its advance exertspressure over overlapping areas.

5. In a road-finishing machine, a carriage mounted on wheels and adaptedto travel on a pair of road rails, two rows of pressure plates mountedin the carriage and extending transversely of the direction of carriagetravel and vertically reciprocable in their mounting, means forreciprocating successively through a definite and predetermined rangethe plates within each row, and a broad transversely extending floatbeam arranged to rearward of the second row of pressure plates.

6. In apparatus for the shaping of a road surface to desired contour, acar mounted to move forward upon spaced-apart rails, a row of verticallyreciprocable .pressure shoes mounted on said car, means forreciprocating said shoes in sequence between predetermined upper andlower limits, and a float beam broad relatively to said shoes arrangedto rearward of said row of shoes for the purpose of preventing the riseof the concrete to rearward of the shoes, the nether side f said beampresenting to the concrete a smooth surface of desired profile.

In testimony whereof I have hereunto setmy hand.

WILLIAM M. VENABLE.

